1. Technical Field
The disclosure relates to electronic device cooling, and particularly to a heat dissipation fan providing stable rotation of a rotor thereof.
2. Description of the Related Art
With the continuing development of electronics technology, electronic packages such as CPUs (central processing units) employed in electronic devices are generating more and more heat. The heat requires immediate dissipation in order that the CPU and the electronic device can continue to operate stably. A heat dissipation fan is commonly used in combination with a heat sink for cooling the CPU.
A conventional heat dissipation fan includes a stator, and a rotor having a hub with a plurality of blades extending from the hub. The stator establishes an alternating magnetic field interacting with a magnetic field of the rotor to drive the rotor to rotate. Thus the rotation of the blades generates a forced airflow, for cooling the heat sink and the CPU. The stator includes a bearing defining a bearing hole therein. The rotor has a shaft extending into the bearing hole and is thus rotatably supported by the bearing.
However, during rotation of the rotor, the rotating blades generate an external pressure which pulls the rotor to move upwardly along an axial direction away from a base of the stator. When this happens, the rotor is said to be in a “floating” condition. The floating rotor is inclined to generate noise, which may be annoying or even unacceptable.
What is desired, therefore, is a heat dissipation fan which can overcome the above-described shortcomings.